Algal Biofuels: Ponds and Promises (Presentation)

50 Pages·2009·4.68 MB·English

Algal Biofuels: Ponds and Promises
13th Annual
Symposium
on Industrial
and
Fermentation
Microbiology
Philip T. Pienkos, Ph.D.
Principal Research
Supervisor
National Bioenergy
Center
May 1, 2009
NREL/PR-510-45822
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.
Biofuel Challenges: Energy Density
Cellulosic ethanol addresses the gasoline market
• U.S. gasoline: 140 billion gallons/year
• Does not address need for higher-energy density fuels

U.S. diesel: 44 on-road/20 off-road billion gallons/year
 U.S. jet fuel: 25 billion gallons/year
Energy Densities
Ethanol Gasoline Biodiesel Diesel/Jet Fuel
76,330 Btu/gal 116,090 Btu/gal 118,170 Btu/gal 128,545/135,000 Btu/gal
Biodiesel Dilemma: TAGs from current oilseed crops cannot come close to
meeting U.S. diesel demand (44 billion gal/year)
– Soy oil crop (2.75 B gal; 2006) could only replace ~4% of U.S. demand
– Cost of biodiesel feedstock high (~$2.50/gallon for soybean oil)
– Vegetable oils must compete with food market
– 2.5B gallon capacity in US, but only 700M gallons produced in 2008
National Renewable Energy Laboratory Innovation for Our Energy Future
Why Fuels from Algae?
• Algae can produce more lipids per acre
than other plants -- potentially 10x - 100x
• Can use marginal, non-arable land
• Can use saline/brackish water
• No competition with food, feed, or fiber
Image courtesy: Q. Hu, ASU
• Can utilize large waste CO resources
2
• Potential to displace significant amount of
U.S. diesel and jet fuel usage
• An algal biorefinery could produce oils,
protein, and carbohydrates and a variety
of other products
Image courtesy: A. Ben-Amotz, Seambiotic
National Renewable Energy Laboratory Innovation for Our Energy Future
Microalgae
• Unicellular photosynthetic
microorganisms
• Thrive in diverse ecosystems
• >40,000 species identified
• Span wide range of taxonomic divisions
• Cyanophyta (cyanobacteria)
• Prochlorphyta
• Glaucophyta
• Rhodophyta (red algae)
• Cryptophyta (cryptomonads)
• Chlorophyta (green algae)
• Euglenophyta
• Chloroarachniophyta
• Pyrrophyta (dinoflaggellates)
• Chromophyta (heterokonts)
Lipid Accumulation in Microalgae
(A) Green microalgae; (B) diatoms; (C) oleaginous species/strains from other eukaryotic algal
taxa; and (D) cyanobacteria. Open circles: Cellular lipid contents obtained under normal growth
or nitrogen-replete conditions. Closed circles: Cellular lipid contents obtained under nitrogen
depleted or other stress conditions.
National Renewable Energy Laboratory Innovation for Our Energy Future
Lipid Yields
Crop Oil Yield
Gallons/acre
Corn 18
Cotton 35
Soybean 48
Mustard seed 61
Sunflower 102
Rapeseed 127
Jatropha 202
Oil palm 635
Algae “10,000”
National Renewable Energy Laboratory Innovation for Our Energy Future
Routes to Algal Fuels
National Renewable Energy Laboratory Innovation for Our Energy Future
What Are the Requirements?
Production of algal oil
Microalgae
requires:
Land
Sunlight
CO2
Water
CO
2
Macro- and micronutrients
Resource Requirements
Soybean Algae*
gal/year
3 billion 3 billion
gal/acre
48 1200
Total acres
62.5 million 2.5 million
Water usage
6 trillion gal/yr
CO fixed
70 million
2
tons/yr
Price per
$4.80 ~$6
gallon
* For algae grown in open ponds with productivity of 10
2
g/M /day with 15% TAG.
9
National Renewable Energy Laboratory Innovation for Our Energy Future
Vast Areas of the Globe Are Not Suitable
for High Levels of Terrestrial Agriculture
But could be used for algal culture.